Method of and apparatus for cooling liquids



June 25, 1929. T. SHIPLEY 1.718.310

METHOD OF AND APPARATUS FOR COOLING LIQUIDS Filed May 1, 1926 4 Sheets-Sheet 1 naw/MP T. SHIPLEY June 25, 1929.

METHOD OF AND APPARATUS FOR COOLING LIQUIDS Filed May 1,1926

4 Sheets-Sheet 2 June 25, 1929.

T. SHIPLEY METHOD OF AND APPARATUS FOR COOLING LIQUIDS Filed May 1, 1926 4 Sheets-Sheet 5 T. SHIPLEY June 25, 1929.

1.718.310 METHOD OF AND APPARATUS FOR COOLING LIQUIDS 4 Sheets-Sheet 4 DMD Filed May 1, 1926 KDV I arm A,

IN VEN TOR A TTORNEYS Patented June 25, 192%.

UNITED. STATES PATEN T OFFICE.

TiromAs SHIPLEY, 0F YORK, PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGNMENTS,

T0 YORK ICE MACHINERY CORPORATION, OF YORK, PENNSYLVANIA, A conno- RATION OF DELAWARE.

METHOD OF AND APPARATUS FOR COOLING LIQUIDS.

Application filed May 1,' 1926. Serial No. 106,165.

This invention relates to refrigeration and particularly to a method 'of cool ng liquids and apparatus operating according to such method. An important field of use is in can ice plants. The present application is a substitute for, and in. part a continuation, of my prior application Serial No. 16,202, filed March 17, 1925.

In= can ice plants, and the like, it has been determined :t-hat the insulating effect of the shell of .ice forming in the can limits the rate of heat abstraction from the water in the cans by the surrounding brine. This limitation is 'so pronounced that a very slowbrine flow is adequate to carry away all the heat that is abstracted.

Slow brine flow around thet cans makes it easy to hold the cans in place, and minimizes the difference in brine level between the two ends of the tank. Someditl'erence but this causes differences in the areas of contact of the brine with the cans, and condifference.

fsequently the rates of freezing are different ":in different portions of: the tank. This difference increases with increased flow in the tank. Hence slow flow in the tank is desirable.

v If the rates of flow against the cans and against the evaporator surface are the same or substantially so it follows that the rate of heat transfer is low. In plants where the evaporator coils are in the tank between rows of cans, the heat transfer rate is ordinarily figured at about .15 B. t. u. per hour per sq. foot per degree mean temperature Theeffect is to consume much valuable space in the tank,'and to require the installation of excessive evaporator surface. i 1 The present application involves the coordination in a novel combination of a number of features; each of which materially affects the performance of others. Heat transfer rates "as high as 180 B. t. u. per

hour per degree inean temperature difference per foot of evaporator surface, have been secured under entirely practicable operating conditions. The operating limit know the chief limiting factor.

the evaporator.

has not yet been reached but there is'substantial reason to believe it is beyond 200 B. t. it. per hour per degree per square foot.

Obviously such a high heat transfer} rate permits a striking reduction in the evaporator surface, with a corresponding economy in installation and operating costs.

To force the heat transfer rate recourse is had to high flow rates of the brine in contact with the evaporator surface. This is practicable if the evaporator be located in a passage which communicates at its ends with opposite ends of the tank. Open channels ofthis type have been used before at moderate heat transfer rates. Quantitative tests prove that a much higher brine flow rate than'can be had in such a channel is needed to secure the results here sought. Hence an enclosing duct in which. a considerable pressure head can be developed was adopted, and is an important feature of the present invention. p

Tests with such ducts indicated that it was practicable to use flow rates for the. brine in the duct so high that the heat 'delivering capacity of the brine stream greatly exceeded the heat abstracting,capacity of ordinary trombone coils. Thus gi definite limit was reached at a heat transfer rate of about 60 B. t. u. per square; foot per de-fl gree mean difference. Investigation showed that at about this rate the evolution of vapor was so rapid that the coils could not be operated v flooded or even approximately flooded. Clearly evaporator capacity was The final step therefore was the development of special types of evaporator designed to set free the vapor developed by evaporation, and" the combination with such evaporators of a refrigerant feed which would at all times maintain the evaporator flooded a nd wl1ich would certainly intercept any l quid refrigerant earriedtoward the suction line by the violentebnllition occurring in Careful coordination of the size of duct, rate of brine; flow and area andform of-. evaporator conduc'es to the best result. The

the liquid line or receiver.

important factors are rapid brine flow, minimum friction flow losses in the brine current, a short discharge path for gaseous re frigerant leaving the evaporator, and maintained flooded operation of the evaporator.

Flooded operation with such violent evaporation as occurs requires the most effective means to intercept liquid refrigerant, and efficiency demands that liquid refrigerant enter the evaporator at or near evaporator temperature. These last results 1 are secured by the use of a suction trap in the suction line, having a connection to' the liquid header and a float controlled feed from By tl's means liquid is intercepted on its way to the suction line, and returned to the evaporator. The rapid flow of gaseous refrigerant to the suction trap and the entrainment of liquid refrigerant thereby has been found to establish an active circulation of liquid refrigerant from the trap to the evaporator and back 'to thetrap and, this contributes to the high heat transfer sought. The connection of the trap to the suction line causes sufficient evaporation of a part of the liquid refrigerant in the trap to cool the remainder to evaporatortemperature- Two practical embodiments of the inven tion are illustrated in the accompanying drawings. Vhere extremely high evaporative rates are used the evaporator first described is to be preferred. The alternative form is simpler to construct and is adequate for heat transfer rates many times those used at present in coil evaporators. The opportunity has been taken to illustrate in Figs. 1 and 6 two slightly different modes of feeding liquid refrigerant to the evaporator. In the. drawings: I Figure 1 is a plan view of the brine tank, showing cans'in place. Some of the cans are omitted in this view.

Figure 2 is a longitudinal section on the line 22 of Figure Figure 3 is a transverse on the line 3-3 of Figure 2. I A Figure 4 is a transverse vertical vertical section section on the kne l-'4 of Figure 2.

Figure 5 1s a fragr gentary transverse verheal section on the hue 5 5 of Figure 2.

Figure 6 is a' view similar to Figure 2, showing a modified construction.

The brine tank is indicated generally by the numeral 11. It is generallyrectangular in form and is preferably of substantially greater length than width. The depth of the tank is preferably such as to leave only a small interval between the bottoms of the cans and-the bottom 12 of the tank, as is clearly indicated in Figurcs2 and 4. Similarly only a slight interval is left between the sides of the tank and the sides of adjacent cans.

' brine circulators.

iVhile other arrangements are possible, I prefer to locate the high velocity duct in which the evaporator is mounted so that it the tank. In this way. it divides the tank into two long and relatively narrow units -so that the flow of brine back through the vextends longitudinally down the middle of v supporting structure for the. cans is secured.

The duct is best shown in Figures 4 and 5. It consists of side plates 13 which are flanged and riveted to the bottom of the tank 12, with whichthey form a tight joint, and which are connected by a channel 14 which forms the top o the duct. At the discharge end. (the right hand end as viewed in Figure"2) the duct terminates at 15, so that ample space is offered for the outflowing brine to distribute itself across that end of the tank preparatory to return flow. v

To steady the structure and also to support the end can units the side plates 13 are extended as shown at 16, and are rigidly connected with the end wall of the tank 11. Atthe opposite end of the tank (i. e., the left hand end in Figure 2) the duct is tightly connected with a head box or manifold, into which brine is pumped from the head end of the tank, and through which such brine flows to the head or inlet end of the duct. This head box, as is indicated the numeral 17 extends the full height of the tank 11. and is closed at the top by a plate 18 as considerable pressure head is developed in the head box by the pumps ,or

This pressure head is indicated by a glass tube 19, which is connected through the plate 18,and which is open at its upper end. Consequently the water column in the tube 19 indicates directly the pressure head at the inlet end of the duct. 7 f

Projecting laterally from the central chamber 17 of the head box-are the lateral extensions 20, whose depth is less, i. e., something less than half the depth of the tank. The central chamber 17 and the extensions 20 are formed .of plates 21, 22, and 23, riveted to the walls of tank 11 and to each other. The top plate 22 of each extension 20 is formed with an aperture-in which is mounted the housing 24 of a-brine circulator, of any suitable t e. In the .drawing I have chosen for i ustration afamiliar 'type of brine circulator making use of a screw propeller 25. Each propeller 25 is driven by any suitable means, such as an electric motor (not shown) mounted on the frame 26. 'The frame 26 is supported on a bracket structure 27 mounted at the head end of the tank 11 and the propeller is driven from a shaft 28 which extends downward through a housing 29. The action of the impellers is to draw brine from the head end of the tank and discharge it into extensions 20 from which it flows into the central chamber 17 and thence into the end of the duct. The side plates 13 and the channel member 14 forming the sides and top of the duct are flanged and tightly connected with the plate 23, as is clearly indicated in Figure 5. a

It follows from the above construction that brine drawn from the tank is delivered to the head end of the duct (the left hand end in Figure 2), flows through this duct to the dischargeend (the right hand end in Figure 2) and there discharges at the end of the tank. The brine flowing through the duct divides, half returning through one side section of the tank and the balance through the other side section.

The cans are mounted inthe tank so that they are spaced a short distance from the head box and a somewhat greater distance from the opposite end of the tank. The mode of mounting the cans is very clearly shown in Figures 1, 2 and 4. The cans are indicated at 30., and in the example, five such cans are mounted permanently in a bar frame 31, thus forming a multiple can unit, whose cans are filled and dumped simultaneously. The bar frames 31 extend longitudinally beyond the end cans of the group, and each frame is supported at one end on the top edge of the side plate 13 of the duct, and at the other end on an angle iron 32 riveted to the side wall of the tank. There is thus no elaborate cansuporting frame work in the tank, and the removal of the cans gives free access to all parts of the tank.

The evaporator is mounted in the duct,

' and is especially designed to operate flooded at all times and to permit a rapid disenagement and discharge of vapor. In the form shown in Figures 1-5, the evaporator consists of two identical units, each consisting of a bottom header 36 and top header 37, and a series of closely spaced vertical riser tubes 38 extending'between the headers. As shown the riser tubes are materially smaller in diameterthan the headers.

In Figure 2 the vertical tubes 38 have been partly omitted at or near midlength of the duct, but it is understood that from end to end of the headers 36 and 37 there are closely spaced vertical connecting tubes 38. At the right end of each bottom header 36 there is an. oil blow-off connection 39 slope or pitch to secure rapi controlled by a valve 40. At the left hand end the two bottom headers 36 are connected with each other by a manifold 41 (see Figure 3), and this manifold 41 is connected by a pipe 42 with a suction trap 43.

A valve 44 is interposed in the pipe 42 tocontrol the flow of liquid refrigerant from the suction trap to the evaporator. I

The left hand ends of the top headers 37 are connected by a manifold 45, which is connected by a pipe 46 with the top of the suction trap 43. A valve 47 is interposed in the pipe 46. The-suction trap 43 is connected by a pipe '48 with the suction side of the compressor (not shown).

The suction trap 43 is connected top and v bottom by pipes 50 and 51 with the top and bottom of a float chamber 52. lVithin the float chamber 52 is a float 53.which controls an inlet valve 54 so as to close valve 54 when the liquid level in chamber 52 i (which is the same as the'level in the trap 43) reaches a given height. The valve 54 modified form of evaporator in Figure 6.

Here the duct structure is essentially the same as that already described, and similar parts are similarly numbered5 In this case the channel member 14 which defines the top ofthe duct is not horizontal as before but is inclined downwardly toward the discharge end of the tank. Also, use is made of a second channel member 60 which is parallel with the inclined channel member 14 and which defines the bottom of the duct at a'point above the bottom of the tank. Otherwise the structure of the duct is unchanged. The purpose of this is to make use of a coil structure 'havin a decided off-flow of the vapor, and at the same time to enclose this evaporator closely by the top and bottom as well as by the ,side walls of the duct.

The evaporator consists of two identical units, each comprising a bottom: header 61, a top header 62, and a plurality of connecting pipes 63 which are sharply bent at one point so that they extend upward vertically from-the bottom header 61, and then extend at an inclination longitudinally through the duct to the top header 62. The bottom headers 61 are connected b a manifold 64 which in turn is connecte with the pipe 42 identical in function with the pipe 45 transfer rate is to 42 previously described. The top manifold 62 is connected through a manifold 65 with a pipe 46 identical in function and essentially identical .in arrangement with the pipe 46 previously described. The tubes 63 are inclined risers and are smaller than the headers.

The arrangement for feeding liquid refrigerant to the evaporator may be identical with that already described, but to disclose the possibility of using other devices a mod ified arrangement. is shown in Figure 6. 'Here the suction trap 43serves. also as the receiver and islarge enough to contain in liquid form all the: refrigerant in" the system. The suction trap 43 receives liquid refrigerant through a pipe 150 which enters the trap 43 at the side and which leads from the float controlled discharge valve of a float trap. Such discharge valve 151 is controlled by a float 152 which is subject to the height of the liquid refrigerant in the shell or.housing 153. The housin '153is connected by a pipe 154 with'the 'bottomof the condenser 155. It follows that the valve 151 opens only so long as there is an accumulation of liquid refrigerant in the shell 153.

The pipe 156 leading from the bottom of housing 153 is intended to deliver refrigerant through'the expansion valve 157 to di rect expansion coils if such-are used in ice storage rooms or the like. The suction connection from such 'direct expansion coils would'lead to the top of trap 43. This is not a feature of the invention but is illus trated merely to indicate the possibility of making such connections if desired.

vThe principal difference between Figures 2 and 6 is in the inclination of the duct and in the construction of the evaporator units. These evaporator units are approximate equivalents. VVhere'a very high heat be used, that shown in Figure 2 is found to be preferable for the reason that the vapor flows away more rap idly, and it can therefore be operated more nearly completely flooded. In both forms off-flowing gaseous refrigerant entrains liquid refrigerant which is intercepted. by

the.trap and returnedto the evaporator, thus establishing a ,useful and very active circulatory flow. The uantity circulated I exceeds by many times tie quantity evaporated.

The construction shown in Figure 6 does not setthe gases free quite so rapidly, and hence .can not be operated at-quite so high a heat transferrate, particularly where the.

tank is long. It can, however, be operated successfully at heat transfer rates which, ,while lower than those feasible with the general'type of evaporator shown in Figure 2,

are nevertheless many .times higher than have heretofore been known, so far as I am adstructure is so proportioned and the brine circulators are'so' operated that there is a brine fiowin the tank of from 20 to 35 feet perminute, and in the duct from 140 to 200 feet per minute. These figures are illustrative and not limiting, and there is reason to, believe that the velocity in the duct can be increased with advantage.

The action of the float trap 53 in conjunctionwith the receiver suction trap 43 is'to insure the maintenance of a substantial head of liquid ammonia on theevaporator coils at all times. This head ordinarily amounts to about 24 inches, but this is not essential, substantially flooded operation being the result sought. The existence of a static head is optional, but is preferred in certain cases. The receiver suction-trap illustrated in Figure 6 is made of such dimensions that it can contain atone time the entire charge of liquid refrigerant in the system. This is of decided advantage for well known reasons.

Not only does the trap 43 maintain in both embodiments of the invention a definite static head on the liquid in the coils, but it operates to intercept liquid ammonia which is drawn through the pipe 46 with the vapor. Further, it serves as .a means to reduce the temperature of the liquid ammonia to a temperature corresponding with the suction pressure. Relatively warm'liquid ammoniaon entering the suction trap 43 will boil under the reduced pressure, the evaporation of a portion of the refrigerant "c'oolingthe remainder to evaporator temperature.

lVhile some of the elements here combined have been known heretofore, they develop in this combination characteristics+which are the result of the combination and which were moval of vapor with its attendant circulation of liquid refrigerant'without danger to the compressor. I The unusual results secured are attributable in part to the combination. defined in 12 certain of the broader claims, and in part tospecial details of coordination in such combination defined in more specific claims. From the method standpoint it appears that the high velocityflow of the brine induces a high velocity flow of the liquid refrigerant in the evaporator, This flow sweeps the gas bubbles that are forming in the tubes away and maintains the heat transmitting efficiency of the tubes. This circulatory flow is the result of a sort of gas-pump action which occurs in relatively restricted passages where the vapor forms sufliciently rapidly. In prior devices the circulatory flow is low and with the small temperature stantial pressure head can be developed, as

contradistinguished from an open ciannel, inwh'ich the rate of flow is'limited.-

The term brine is used in the specification and claims in a generic sense to define any liquid which does ,not freeze at the temperature maintained by the evaporator.

What I claim is: q

1. The combination of a brine tank; a flow enclosing .duct communicating at its ends withsaidtank; an evaporator cooler comprising headers and, connecting risers in said duct; and means for drawing brine from said tank and forcing it under pressure head through said duct and back into said tank.

2. The combination of a brine tank; a flow enclosing duct communicating at its ends with opposite ends of said tank; an evaporator cooler in said duct including headers and risers, said cooler extending substantially the full height and width of the duct, and throughout substantiall the entire-length thereof; .and means for rawing brine from said tank andpforcing it under pressure head through said duct and back into said tank.

3. The combination of a brine tank; a

. flow enclosing duct communicating at its ends with said tank; an evaporator cooler in said duct comprising headers and risers; means for drawing brine fromsaid tank and forcing it under pressure head through said duct and back-into said tank, said brine forcingmeans being operable at such a rate and said tank and duct being so proportioned that the lineal flow rate through the 'tank is of the order of 20 feet and not exceeding "35 feet per minute, and the flow rate through the duct is of the order of 165 feet and not less than 140 feet per minute.

4. The combination of a brine tank; a flow enclosing duct communicating at its ends with said tank; means for drawing brine from said tank and forcing it under pressure head through said duct; and an evaporator cooler in said duct, said cooler including a pair of headers and a plurality of hollow single pass risers each connected at its opposite ends with said headers, the point ofconnectionof each riser'with one header being below the point of connection header adjacent the bottom "of said duct,

anda top header adjacent the top of said duct, and a plurality of risers extending in an approximately vertical direction and connected with said headers.

6. The combination of a brine tank; a flow enclosing duct communicating at its .ends with said tank; means for drawing brine from said tank and forcing it under pressure head through said duct and back into said tank; an evaporator cooler in direct contact with the brine flowing through said duct, Said evaporator being constructed .and arranged to offer short and relatively restricted upward flow paths for refrigerant vapor; a suction trap; a liquid connection from the lower lower portion 0 said evaporator; a vapor connection from the upper portion of said evaporator to the upper portion of said trap; a suctionconnection from the upper portion of .said trap; and means for delivering liquid refrigerant to said suction trap.

7. The combination of a brine tank; a flow enclosing duct communicating at its ends" with said tank; means for drawing brine from said tank and forcingit under pressure head through said duct and back into said tank; an evaporator in direct contact with the brine flowing through said duct, said evaporator being constructed and arranged to oifershort and relatively 'restricted upward flow paths for refrigerant portion of said trap to the vapor; a suction trap; a liquid connection" from the lower portion of said suction trap to the lowerportion of said evaporator; a-

connection for gaseous and entrained liquid refrigerant from the upper portion of said evaporatorto the upper portion of said suction trap; a suction connection from said trap; a condenser; and float controlled valvemeans for delivering liquid refrigerant from said condenser to said. suction trap.

8. The combination of a brine tank; a

flow enclosing duct communicating at its ends with. said tank; means for drawing brine from said tank and forcing it under pressure head through said duct and back into said tank; an evaporator cooler extending substantially the entire length of said duct and having heat transfer surfaces distributed in spaced relation over substantially the entire transverse area of said duct, said evaporator cooler including'an inlet header, a discharge header, and a plurality of riser tubes connected with said headers and having a rising gradient at all points from the inlet to the discharge header.

9. The combination-of a brine tank; a flow enclosing duct communicating at its ends with said tank; means for drawing brine from said tank and forcing it under pressure head through said duct and back into said tank;'an evaporator cooler extending substantially the entire length of said duct, said evaporator cooler including, a

lower inlet, header, anupper discharge header, and a plurality of tubular members connecting said headers; a suction tr'ap mounted at an elevation above said discharge header; and connections one from the discharge header to the upper portion of the suction trap and the other from the lower portion of the suction trap to the inlet header.

10. The combination of a. brine tank; a flow enclosing duct communicating at its ends with said tank; means for drawing brine from said tank and forcing it under pressure head throughsaid duct and back to said tank; an evaporator cooler including an inlet header, a discharge header and a plurality of tubes connecting said headers, said evaporator cooler being mounted in said duct so that all parts of the brine current are brought into active heat exchanging relation with said tubes; a suction trap mount ed at an elevation above the discharge header; connections between said trap and evaporator, one a liquid conducting connection from the trap to the inlet header and another a combined gas and liquid conducting connection'from the discharge header to the trap, whereby a closed liquid circuit through the trap and evaporator is afforded; a suction means for feeding liquid refrigerant to said circuit.

I L'The combination of a brine tank; a flow enclosing duct communicating at its ends with said tank; an evaporator insaid duct including a plurality of restricted refrigerant passages with intervening brine passages, and headers," one for feeding liquid to the restricted passages and another for receiving. gaseous and entrained liquid refrigerant from said passages; a suction trap; a suction connection leading from said connection leading from said trap; and,

trap; a liquid connection leading from said trap to the first header; a connection for gas and entrained liquid leading from the second header to the trap, whereby a closed liquid circuit 'through the evaporator and trap is afforded; means for feeding liquid refrigerant to said circuit; and means for drawing brine from said tank and forcing it under pressure head through said duct and back into said tank.

12. The combination of a brine tank; a

tion from the evaporator""to the trap; a

suction connection for withdrawing gaseous refrigerant from said trap; 'uid refrigerant; and liquid-level controlled automatic means for feeding refrigerant from said source to saidtrap and evaporator to maintain a liquid level therein above the top of the evaporator.

13. The combination of a brine tank; a flow enclosing duct communicating at its ends with said tank; means for drawing brine from said tank and forcing it under pressure head through said duct and back .into said tank; an evaporator in direct contact with brine flowing through said duct, said evaporator including headers, one substantially higher than the other and intervening smaller risers; a'suctidmap extending higher than the upper header; a liquid a source of liqconnection from the lower portion of the V trap to the lower header; a return connec-' tion from the upper header to the upper portion of the trap; a suction connection for withdrawing gaseous refrigerant from the trap; a source of liquid refrigerant; and a float controlled valve controlling the flow of liquid refrigerant from said source to said trap and evaporator and operating to maintain a liquid level above the top of the upper header.

v14. The method of cooling liquids, which consists in circulating the liquid to be cooled over one face of a surface heat exchanger,

whose other face is in contact with a volatile liquid refrigerant, at such a rate that the conveyed heat will cause active vaporization of the refrigerant; causing such vaporization to develop an entraining actionon the liquid refrigerant; and applying such entraining action to produce a rapid flow of liquid refrigerant over said heat exchanging surface.

15. The method of cooling liquids, which consists in circulating the liquid to be cooled over one face of a. surface heat exchanger, passage, having a rising gradient; and apwho'se other face is" in contact with a 'volat-ile plying such entraining action to produce a. liquid refrigerant, at such a. rate that the rapid flow of liquid refrigerant over said 1 conveyed heat will cause active vaporization heat exchanging surface. 5 of the refrigerant; developing an entrain- In testimony whereof I have signed my ing action on the liquid refrigeranbby causname to this specification.

ing such v'a-porization to-occur in a restricted THOMAS SH IPLEY. 

